Effect of clayey media parameters on the negative response of a coincident loop¹

Abstract

The aim of this work is to consider the phenomenon of negative response and its detectability in a polarizable half-space formed of Clay-water mixture which commonly exists in water aquifers and which can be used as a simple indicator of the presence of Underground water.We make use of an analytical treatment for the transient voltage induced in a coincident loop lying on a half-space as a basis for our computations. A Cole-Cole model is used to represent the Clay with appropriate parameters.As saturated Clay is characterized by high conductivity and moderate chargeability, it is hardly detectable relative to the practical noise level. However, there are optimum Clay parameters that offer a maximum negative response. It is also observed that for a very short time constant z in the Cole-Cole model, the amplitude of the negative response decreases with the decrease of the time constant due to the fast decay of the polarization current.Finally, it is found that there is an optimum value for the loop radius which gives the largest value of the negative response and this loop radius depends on the model parameters.

Time‐domain electromagnetic imaging of a clayey confining bed in a brackish environment: A case study in the Kairouan Plain Aquifer (Kelbia salt lake, Tunisia)

“…On Profile 3, only sounding 33 has a clearly distinguishable change in sign at the late times of the measured data. This is most probably due to an induced polarization (IP) response from the ground (El-Kaliouby, Hussain, Bayoumi, El-diwany, & Hashish, 1995;Flis, Newman, & Hohmann, 1989). The extremely low resistivity (less than 10 Ωm) of the environment means that the signal induced by the electrical conductivity overrides the responses from the magnetic or dielectric ground properties.…”

Influence of dispersive soil electromagnetic properties on hand‐held time domain electromagnetic sensors

“…With change of integration variable r = Rt sin ψ, the response is readily evaluated numerically employing a GaussLaguerre quadrature formulation (El-Kailouby et al 1995). Results presented by Lee (1981) for specific Cole-Cole parameters, were confirmed independently by Raiche (1983) by way of an alternative computational method.…”